This article aims to accomplish two goals. The ﬁrst is to introduce some of the morecommon statistical measures of biodiversity to the empirical study of law. The second is to measure the diversity of background on the current Supreme Court using diversity indices commonly used in ecology. We treat the Supreme Court as if it is an ecosystem, and life experiences and traits as if they are different species, and ask whether diversity in seven categories (race/ethnicity, religion, professional background, geographic background, economic background, education, and political party) has grown or shrunk over time. We then combine these categories to create a single overall diversity measure. The results demonstrate that although the current Supreme Court is more diverse overall than the long-term historical average, there has been a recent downward trend in overall diversity,driven by decreases in diversity of educational background, geographic background, and,to a lesser extent, religious diversity. However, diversity of professional background and of childhood economic background has remained high in recent years, and racial diversity has increased greatly.